1. Field of the Invention
The present invention relates to a motion picture camera, and particularly to a compact, lightweight self-blimped camera that is sufficiently quiet for sound movie production.
2. Description of the Prior Art
For commercial sound motion picture photography, the camera must be extremely quiet so that it will not emanate noises which can be picked up and recorded by the movie sound system. In the past, noise elimination generally has required the use of "blimped" cameras wherein the camera is mounted in a large soundproof housing called a "blimp". The camera itself may be quite small and relatively light, typically about 25 pounds, but the blimp is very bulky and might weigh as much as 100 pounds. Use of a blimped arrangement thus substantially limits camera mobility.
There are many noise sources in the typical prior art movie camera. Paramont among these is gear noise generated by the multiple metal gears used in the film mechanism. One object of the present invention is to provide a camera using no gears in the drive train. Another noise source is the bearings. Even ball bearings produce noise, and it is a further object of the present invention to provide a camera using only sleeve bearings which produce minimal noise.
The camera case itself may act as a noise radiator. Thus where the rigid metal case is used as the support member for the gear drive train, the acoustic radiation efficiency is increased, resulting in a higher noise level. A further object of the present invention is to provide a camera in which the entire camera mechanism is mounted on a frame that resiliently floats within the outer case, so that noise radiation via the case is minimized.
A problem with achieving this in the past concerns the lens mount. There must be a rigid relationship between the lens support and the film transport mechanism. If the lens mount were affixed to the camera case, the film transport components themselves must be rigidly mounted to the case. But this would defeat the use of a floating film assembly. Thus another object of the present invention is to provide a camera having a unique lens mount that itself is resiliently isolated from the camera housing.
Another problem associated with prior art lens mounts is that of size and complexity. Most movie cameras use a rotating shutter that "opens" each time that a film frame is positioned and is temporarily stationary in the transport movement. Advantageously the camera also has an optical path that permits viewing of the scene through the lens during times that the shutter is "closed". This may necessitate use of a rotating mirror that is positioned in the lens light path in alternation with the shutter. Complex mechanical arrangements are necessary to accommodate the rotating mirror and shutter components, often complicating the lens mount design. An object of the present invention is to provide a simplified lens mount that readily accommodates the through-the-lens viewing components.
An overall object of the present invention is to provide a compact motion picture camera that is sufficiently quiet so as to be useful for studio sound movie production without the use of a "blimp". The camera thus provides excellent mobility, giving the cameraman more freedom than previously possible. The camera also can be used for portable assignments, as it need not be tripod mounted, but can readily be hand carried or shoulder mounted while in use.